JP2515739B2 - Processing method and processing apparatus for display element substrate - Google Patents

Description

The present invention relates to a method and an apparatus for processing a display element substrate.

[Conventional technology]

At present, the most popular type of flat display device is a field effect liquid crystal display device.

Various types of field effect liquid crystal display elements are well known, with a twisted nematic (TN type) liquid crystal display element being a representative example. An example of the TN type liquid crystal display device is shown in FIG. In this liquid crystal display element, an upper substrate 1 and a lower substrate 2 each made of transparent glass or the like have a predetermined interval, for example, 5 to
Sealing members 3 made of, for example, frit glass or an organic adhesive are arranged in parallel with each other at 15 μm.
The nematic liquid crystal 4 having a positive dielectric anisotropy is sealed in the internal space formed by these. The predetermined interval is obtained by the spacer 5 such as fiber glass or glass powder mixed in the sealing member 3. The sealing member 3 may also be used as a spacer without using the spacer 5.

The upper electrode 6 and the lower electrode 7 are formed in a predetermined pattern on the inner surface of each of the upper and lower substrates 1 and 2 by a transparent conductive film, and liquid crystal molecules in contact with the liquid crystal 4 are formed on the surface in contact with the liquid crystal 4. Liquid crystal orientation control films 8 and 9 having a constant film thickness for orienting in a desired constant direction are formed. Such an orientation control film 8,9
Is formed by a so-called rubbing treatment in which an organic polymer thin film or an inorganic thin film is applied on the surface of a substrate having upper and lower electrodes 6 and 7, and the surface is rubbed in a certain direction with cotton or the like (Japanese Patent Publication No. 58- 23610 publication).

The liquid crystal orientation control film 8 of the upper substrate 1 has a first fixed direction as the orientation direction of the liquid crystal molecules, and the liquid crystal orientation control film 9 of the lower substrate 2 has an orientation.
The second constant direction is selected as the orientation direction of the liquid crystal molecules according to the above, and the respective directions are made different, so that the molecules of the nematic liquid crystal 4 sandwiched between the upper and lower substrates 1 and 2 have their long axes up. , Are substantially parallel to the surfaces of the lower substrates 1 and 2 and are twisted and oriented from the first direction toward the second direction. The angle formed by the first direction and the second direction, that is, the twist angle of the liquid crystal molecules is arbitrarily selected, but is generally about 70 to 270 degrees.

An upper polarizing plate 10 and a lower polarizing plate 11 are arranged outside the substrates 1 and 2, respectively. The polarization axes of the polarizing plates 10 and 11 are arranged so as to form an angle of 0 to 90 degrees with the alignment directions of the liquid crystal alignment control films 8 and 9, respectively.

When such a display element is observed from the upper substrate 1 side, a light guide body such as an acrylic resin plate or a glass plate having a desired thickness is inserted between the reflection plate 12 and the back surface of the lower polarizing plate 11, As a reflective display element with a light source arranged at an appropriate place on its side surface,
Alternatively, it is used as a transmissive display element in which a light source (not shown) is arranged instead of the reflection plate 12.

[Problems to be solved by the invention]

When rubbing the liquid crystal alignment control film, static electricity generated by friction is discharged and the liquid crystal alignment control film, the electrode pattern formed under the liquid crystal alignment control film, or TF described later.
There was a problem that T etc. were destroyed. Conventionally, static electricity is neutralized by humidity control, O ₃ blow, etc., all electrode patterns are short-circuited only during rubbing treatment, or discharge auxiliary patterns are provided (JP-A-60-182413, 60-237429, 60- 237
No. 430), or a rubbing treatment using a blended fabric of conductive carbon fibers and non-conductive chemical fibers (JP-A-61-15129).
However, there was room for improvement and it was not completely satisfactory. Although the rubbing treatment of the liquid crystal display element has been described above as an example, it is not limited to the rubbing treatment, and the application of the liquid crystal alignment film or the processing of the surface of the substrate for general display elements, for example, the static electricity removal even at the time of the photoresist application Improvement is desired.

[Means for solving problems]

The above problems are caused by sprinkling ionized air to eliminate static electricity generated during processing of the display element substrate surface, and the substrate surface to be processed is 5 mm or more between this and the object surface having almost the ground potential. It is solved by interposing and holding the insulating layer.

[Action]

During processing of the substrate surface, static electricity generated on the substrate surface is sprinkled with ionized air to eliminate static electricity, because ions are attracted along the electric field generated in the space around the substrate charged by the static electricity. Therefore, in the case where the amount of charge is constant, if the electric field strength due to this is maximized, the static elimination effect is effectively performed.

By holding the surface of the substrate to be processed away from the object surface, which has almost the earth potential, by a certain value or more, and reducing the ground capacitance formed by this substrate surface, the relationship of electrostatic voltage = charge amount / ground capacitance is obtained. The electrostatic field can be effectively eliminated by increasing the charged voltage and thus the electric field.

〔Example〕

An embodiment of the present invention will be described below by taking a liquid crystal display element as an example.

First, an active matrix color liquid crystal display element in which electrostatic breakdown due to friction during rubbing the liquid crystal orientation control film is a particular problem will be described. Active matrix liquid crystal display element using TFT array,
Amorphous Si TFT or poly Si TFT is used.

FIG. 3 is a partial sectional view of an amorphous Si TFT liquid crystal display device.
A gate insulating film 22 is covered thereover, and further an amorphous Si layer 23, a drain 24, a source 2 as a semiconductor body for TFT.
5, transparent display electrode 26, T electrically connected to this source 25
Protective film 27 for covering FT, light shielding layer 28 for shielding TFT from light
Is provided. Here, arm electrode 21, amorphous Si layer 23, drain 24, source 25, transparent display electrode 26, protective film
27 and the light shielding layer 28 are arranged periodically at the pitch of the pixels of the liquid crystal display element. Further, a liquid crystal alignment control film 9 made of an organic polymer film is formed on the uppermost layer of the lower substrate 2. The nematic liquid crystal 4 has a twisted structure as described with reference to FIG. On the other hand, inside the upper substrate 1, a color filter 29 is first formed, then a counter electrode 30 made of a transparent conductive film, and a liquid crystal alignment control film 8 made of an organic polymer film. Also, upper and lower polarization plates 10 and 11 are provided outside the upper and lower substrates 1 and 2, respectively.

FIG. 4 is a partial cross-sectional view of a polysilicon TFT liquid crystal display device. First, a poly Si layer 33 formed by low pressure CVD, electron beam evaporation, MBE, etc. is formed on a lower substrate 32. Further, the gate electrode 31 is formed via the SiO ₂ insulating film 37 formed by thermal oxidation. A source line 35 is connected to one end of the poly-Si layer, and a drain 38 connected to the pixel electrode 36 is formed at the other end. Further, a liquid crystal alignment control film 9 is formed on the uppermost layer of the lower substrate 2. Liquid crystal layer 4,
Upper substrate 1, liquid crystal alignment control film 8, color filter 29, counter electrode 3
The 0, upper and lower polarizing plates 10 and 11 are the same as described in connection with FIG. 3 (for details, see, for example, the journal of the Television Society).
Vol.40, No.3 (1986) pp. 170-177).

The rubbing process for the liquid crystal alignment control films 8 and 9 in FIGS. 3 and 4 is performed after forming the organic polymer film on the upper substrate 1 and the lower substrate 2.
It is applied before the upper and lower substrates are arranged facing each other and fixed (details are described in, for example, the November 24, 1980 issue of Nikkei Mechanical).

Then by sprinkling the ionized air,
The charge removal on the surface of the substrate that has been rubbed will be described.

As shown in FIG. 5, for example, the lower substrate 2 having the liquid crystal orientation control film 9 described with reference to FIG. 3 is fixed to the metal vacuum suction plate 51 placed on the base 53, and is fixed to the roller 54. The surface of the liquid crystal alignment control film 9 is rubbed by the wound buff cloth 55. At that time, the ion blower 56 (for example, A202 type Porta Blower of Simco Japan Co., Ltd.) ionizes the air molecules into plus and minus and sprinkles them on the liquid crystal alignment control film 9 to generate the liquid crystal alignment control film 9 by rubbing.
Ions having a polarity opposite to that of the upper charge are attracted to this charge and neutralize the charge on the liquid crystal alignment control film 9.

Considering the case where the lower substrate 2 is made of a glass plate having a thickness of 1 mm, the capacitance to ground is about 3 pF / cm ² . Therefore, assuming that the amount of electrified charge is −300 pC / cm ² , the charged voltage is −100V.
When the charging voltage is low, the electric field is weak, so
Since the force of attracting the ions from the ion blower 56 is weak, it takes time to remove the charge from the liquid crystal alignment control film 9. If the amount of positive ions and the amount of negative ions from the ion blower 56 are not balanced, charge is induced from the ground side to the lower side of the lower substrate 2 and the charge amount on the front and back sides of the lower substrate 2 However, if the lower substrate 2 is removed from the vacuum suction plate 51 after this, the opposite substrates will be charged with the opposite sign, and the effect of neutralization will not be obtained. Therefore, the static elimination characteristics according to the configuration of FIG. 5 are as shown by the curve A in FIG.

 An embodiment of the present invention will be described below.

Referring to FIG. 1, a lower substrate 2 having a liquid crystal orientation control film 9 is fixed on a vacuum suction plate 51, and the vacuum suction plate 51 is mounted on a base 53 via a spacer 52 made of an insulating material. There is. Here, the spacer 52 is made of styrene resin having a thickness of 10 mm. As in FIG. 5, the surface of the liquid crystal alignment control film 9 is rubbed by the buff cloth 55 wound around the roller 54, and the electrostatic charges generated on the liquid crystal alignment control film 9 are removed by the ion blower 56. The static elimination characteristics in this embodiment are shown by the curve B in FIG.
Indicated by. That is, in the present embodiment, unlike the case of eliminating the static electricity by the configuration of FIG. 5, the static elimination is achieved rapidly.

In this embodiment, the distance between the object surface having the ground potential and the upper surface of the substrate is (substrate thickness + spacer thickness), that is, 11 mm.
Since the insulating layer of is installed, the capacitance to ground is about 0.09pF / c
the m ^2. Therefore, when the electrification is made to be −3000 pC / cm ² as in the case of FIG. 5, the electrification thickness becomes 3300V. Therefore, since the electric field due to this is also large, the force from the ion blower 56 for attracting ions having the opposite sign to the charged charges is large, and the charge can be quickly eliminated. Further, since the capacity to ground is small, even if there is an imbalance between the amount of positive ions and the amount of negative ions blown from the ion blower 56, there is little induction from the ground due to this and the imbalance of ions does not pose a problem.

The present invention, in order to eliminate static electricity generated on the processed surface of the substrate surface, when the ions are sprinkled on the surface of the substrate, by minimizing the ground capacitance formed by the upper surface of the substrate, the electrostatic voltage due to the static electricity, and thus the electric field. Is increased to efficiently attract the ions to the surface of the substrate, thereby quickly and completely eliminating static electricity.

In the present invention, if an insulating layer having a thickness of 5 mm or more is interposed between the substrate surface during processing and the object surface having a ground potential, static electricity advantageous for static electricity removal generated during actual substrate surface processing can be obtained. It can be lowered to the electric capacity. As a method of interposing the insulating layer between the substrate surface during processing and the object surface having the earth potential, a spacer made of an insulator is interposed between the lower surface of the substrate and the object surface having the earth potential.
If a spacer having a small dielectric constant ε is used to form this spacer, the spacer can be made thinner.
As the spacer material, styrene, polypropylene, Teflon, etc. showed good results. When the spacer is made of Teflon with a substrate thickness of 1 mm, the relative permittivity is 2, so the spacer thickness is preferably 20 mm or more.
An effect of about 10 mm can be seen, but it is not sufficient. It was also found as a result of the experiment that the one having a small dielectric loss shows a good result. Bakelite is not preferable because it has a large dielectric loss and induces it.

A hollow layer may be provided between the substrate and the upper surface of the base 53, which is an object having a ground potential, by using the spacer 52 in FIG. 1 as a frame.

The vacuum suction plate 51 used in the above embodiment is usually made of metal, but the area is preferably as small as possible from the viewpoint of not increasing the ground capacity of the substrate 2, and it is not preferable to make it much larger than the size of the substrate 2. . Of course, the vacuum suction plate 51 may be omitted and the substrate 2 may be positioned and fixed by the outer shape of the substrate 2.

In general, it is preferable that the electrostatic capacitance between the upper surface of the substrate and the ground is 1 pF / cm ² or less in order to quickly and completely eliminate static electricity during substrate processing such as rubbing treatment.

According to the present invention, static electricity can be eliminated quickly and completely even when a substrate on which an amorphous Si TFT or poly Si TFT which is easily destroyed by static electricity is already formed is further processed. , Amorphous Si TFT or Poly Si TFT can be completely prevented from electrostatic damage.

Although the above-mentioned examples are about the static elimination action when rubbing the liquid crystal alignment control film, the present invention is not limited to this, and when the liquid crystal alignment control film is printed on the substrate surface by the roller. Of course, it can also be applied to static elimination of static electricity that occurs when a photoresist material is printed on the surface of a substrate by rollers. Therefore, the present invention is not limited to the substrate processing of the liquid crystal display element, but can be applied to the substrate processing of other display elements, for example, the electronic display element.

〔The invention's effect〕

According to the present invention, static electricity generated during processing of a display element substrate can be quickly and completely eliminated.

[Brief description of drawings]

FIG. 1 is a side view for explaining an embodiment of the present invention, FIG. 2 is a sectional view of a liquid crystal display element, FIGS. 3 and 4 are partial sectional views of an active matrix liquid crystal display element, and FIG. The figure for demonstrating the static elimination of the substrate surface by an ion blower, 6th
The figure is a graph for explaining the static elimination characteristics according to the present invention. 2 ... Lower substrate, 9 ... Liquid crystal alignment control film, 51 ... Vacuum adsorption plate, 52 ... Spacer, 53 ... Base, 54 ... Roller, 55
…… Buff cloth, 56 …… Ion blower.

Claims (6)

(57) [Claims] 1. A method of processing a display element substrate made of an insulating material, wherein when ionized air is sprinkled to eliminate static electricity generated during surface processing of the display element substrate surface,
5m between the surface of the substrate and the surface of the object that has almost the earth potential
A method of processing a display element substrate, characterized in that an insulating layer having a thickness of at least m is interposed and held. 2. The display device according to claim 1, wherein the substrate surface is held so that the electrostatic capacitance formed with respect to the ground potential surface is 1 pF / cm ² or less. Substrate processing method. 3. A cylindrical processing member that contacts the surface of a display element substrate while rotating to process the substrate surface, an ion generator that sprinkles ionized air on the surface of the substrate, and the display element substrate. In a processing device for a display element substrate including a mounted base, a display element substrate characterized by comprising a spacer for holding a display element substrate surface to be processed at a distance of 5 mm or more from a base upper surface. Processing equipment. 4. The display device substrate processing apparatus according to claim 3, wherein the spacer has a plate shape made of an insulating material. 5. The spacer according to claim 3, wherein the spacer is a frame-like body that forms a hollow layer between the surface of the display element substrate to be processed and the upper surface of the base. Display element substrate processing equipment. 6. The processing device for a display element substrate according to claim 4, wherein the insulating material is made of a material having a relative dielectric constant of 5 or less.